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Biomedical subjects

S R Inman

Publications and source records attributed to S R Inman.

23 records · Page 2Linked to original sources
PubMed1993

Renal vascular response to vasodilators following warm ischemia and cold storage preservation in dog kidneys.

The purpose of this study was to determine whether warm ischemia (WIT) and cold storage preservation (CSP) impair endothelium-dependent vascular relaxation in the kidney. Twenty-four canine kidneys were harvested, preserved with CSP for 24 or 48 hours, and then perfused with canine blood at 37 C for the determination of glomerular filtration rate (GFR), perfusion flow rate, and renal vascular resistance (RVR). There were four experimental groups: Group I--no WIT followed by 24 hours CSP, Group II--30 minutes WIT followed by 24 hours CSP, Group III--no WIT followed by 48 hours CSP, Group IV--30 minutes WIT followed by 48 hours CSP. Endothelial function in each group was evaluated using acetylcholine (ACh, 1 mg. bolus) as an endothelial dependent vasodilator, and sodium nitroprusside (NP, 10 mg. bolus) as an endothelial independent vasodilator. Glomerular filtration rate was significantly less (P < .05) and RVR was significantly greater (P < .05) for kidneys from Groups II, III and IV compared to group I. The highest RVR was observed in kidneys from Groups II and IV. Nitroprusside administration caused an equivalent reduction in RVR among all four study groups. ACh administration caused a similar reduction in RVR in Groups I and III; however, the change in RVR was significantly less in Groups II and IV (P < .05). We hypothesize that the more severe ischemic insult in the latter groups led to vascular endothelial damage with a consequent loss of ability to secrete endothelium-derived relaxing factor in response to ACh administration.

Acetylcholine↗
PubMed1977

The gallium melting-point standard: its application and evaluation for temperature measurements in the clinical laboratory.

We are impressed with the ease and certainty of calibration electronic thermometers with thermistor probes to +/- 0.01 degree C at the gallium melting point, 29.771(4) degrees C. The IFCC reference method for measuring aspartate aminotransferase activity in serum was run at the reaction temperature of 29.771(4) degrees C. By constantly referencing to gallium as an integral part of the assay procedure, we determined the absolute reaction temperature to IPTS-68 (International Practical Temperature Scale of 1968) to +/- 0.02 degrees C. This unique temperature calibration standard near the center of the range of temperatures commonly used in the clinical laboratory is a valuable addition and can be expected to improve the accuracy of measurements, especially in clinical enzymology.

Aspartate Aminotransferases↗
PubMedDate not supplied

Preglomerular and postglomerular blood flow: relationship to kidney disease and treatment.

BACKGROUND: In the kidney, the afferent and efferent arterioles normally constrict or dilate in response to changes in systemic blood pressure to maintain glomerular filtration while protecting the glomerulus from excessive pressure. In diabetes mellitus and hypertension, the two most common causes of kidney failure, sustained hypertension within the glomerulus damages the glomerular membrane and eventually results in loss of kidney function. SUMMARY: Techniques developed in the last 10 years allow direct study of the glomerulus and the glomerular circulation. In both diabetes and hypertension, the afferent vessels may dilate, resulting in excessive pressure in the glomerulus. Calcium antagonists, angiotensin-converting enzyme inhibitors, and cyclosporine have direct effects on the preglomerular and postglomerular vessels, and the afferent and efferent arterioles may respond differently to the same agent. CONCLUSIONS: Techniques for studying afferent and efferent arteriolar changes and glomerular filtration rate may provide important insights into the actions of drugs and into renal diseases. Clinicians are beginning to be able to select drugs that have desired effects on the renal microcirculation.

Animals↗
PubMedDate not supplied

Role of the renal microcirculation in antihypertensive therapy.

BACKGROUND: The renal circulation plays a central role in regulating blood pressure and glomerular filtration. OBJECTIVE: To examine the effects of the various classes of antihypertensive agents on the renal microcirculation. SUMMARY: Peripheral vascular resistance is generally increased in hypertension, and the microcirculation makes the major contribution to resistance. In the kidney, the preglomerular and postglomerular vessels constrict to protect the glomerular capillary from increased hydrostatic pressure, further increasing peripheral resistance. Because the renal microcirculation adjusts to maintain glomerular filtration and blood flow, antihypertensive agents that can normalize the pressure and blood flow in these vessels may help prevent the long-term consequences of hypertension. Angiotensin-converting enzyme inhibitors directly affect preglomerular and postglomerular resistance, but they further decrease postglomerular resistance. Calcium antagonists selectively decrease preglomerular resistance. The diuretics, vasodilators, alpha blockers, and beta blockers may also cause changes in preglomerular and postglomerular resistance; however, compensatory reflex responses may mitigate their direct effects. CONCLUSION: Some antihypertensive agents have unique actions on the renal microcirculation that better maintain renal function. A basic understanding of the physiologic action of these agents on the microcirculation may help in their selection.

Antihypertensive Agents↗